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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package AST
import Scanner "scanner"
type (
Any interface {};
Type struct;
Expr struct;
Stat struct;
Decl struct;
)
// ----------------------------------------------------------------------------
// Lists
//
// If p is a list and p == nil, then p.len() == 0.
// Thus, empty lists can be represented by nil.
export type List struct {
a *[] Any;
}
func (p *List) Init() {
p.a = new([] Any, 10) [0 : 0];
}
func (p *List) len() int {
if p == nil { return 0; }
return len(p.a);
}
func (p *List) at(i int) Any {
return p.a[i];
}
func (p *List) set(i int, x Any) {
p.a[i] = x;
}
func (p *List) Add(x Any) {
a := p.a;
n := len(a);
if n == cap(a) {
b := new([] Any, 2*n);
for i := 0; i < n; i++ {
b[i] = a[i];
}
a = b;
}
a = a[0 : n + 1];
a[n] = x;
p.a = a;
}
func (p *List) Pop() Any {
a := p.a;
n := len(a);
var x Any;
if n > 0 {
x = a[n - 1];
a = a[0 : n - 1];
p.a = a;
} else {
panic("pop from empty list");
}
return x;
}
func (p *List) Clear() {
p.a = p.a[0 : 0];
}
export func NewList() *List {
p := new(List);
p.Init();
return p;
}
// ----------------------------------------------------------------------------
// All nodes have a source position and and token.
export type Node struct {
pos, tok int;
}
// ----------------------------------------------------------------------------
// Expressions
export type Expr struct {
Node;
x, y *Expr; // binary (x, y) and unary (y) expressions
// TODO find a more space efficient way to hold these
s string; // identifiers and literals
t *Type; // type expressions, function literal types
block *List; // stats for function literals
}
func (x *Expr) len() int {
if x == nil {
return 0;
}
n := 1;
for ; x.tok == Scanner.COMMA; x = x.y {
n++;
}
return n;
}
export func NewExpr(pos, tok int, x, y *Expr) *Expr {
if x != nil && x.tok == Scanner.TYPE || y != nil && y.tok == Scanner.TYPE {
panic("no type expression allowed");
}
e := new(Expr);
e.pos, e.tok, e.x, e.y = pos, tok, x, y;
return e;
}
export func NewLit(pos, tok int, s string) *Expr {
e := new(Expr);
e.pos, e.tok, e.s = pos, tok, s;
return e;
}
export var BadExpr = NewExpr(0, Scanner.ILLEGAL, nil, nil);
// ----------------------------------------------------------------------------
// Types
export const /* channel mode */ (
FULL = iota;
SEND;
RECV;
)
export type Type struct {
Node;
expr *Expr; // type name, array length
mode int; // channel mode
key *Type; // receiver type, map key
elt *Type; // array element, map or channel value, or pointer base type, result type
list *List; // struct fields, interface methods, function parameters
}
func (t *Type) nfields() int {
nx, nt := 0, 0;
for i, n := 0, t.list.len(); i < n; i++ {
if t.list.at(i).(*Expr).tok == Scanner.TYPE {
nt++;
} else {
nx++;
}
}
if nx == 0 {
return nt;
}
return nx;
}
export func NewType(pos, tok int) *Type {
t := new(Type);
t.pos, t.tok = pos, tok;
return t;
}
// requires complete Type type
export func NewTypeExpr(t *Type) *Expr {
e := new(Expr);
e.pos, e.tok, e.t = t.pos, Scanner.TYPE, t;
return e;
}
export var BadType = NewType(0, Scanner.ILLEGAL);
// ----------------------------------------------------------------------------
// Statements
export type Stat struct {
Node;
init, post *Stat;
expr *Expr;
block *List;
decl *Decl;
}
export func NewStat(pos, tok int) *Stat {
s := new(Stat);
s.pos, s.tok = pos, tok;
return s;
}
export var BadStat = NewStat(0, Scanner.ILLEGAL);
// ----------------------------------------------------------------------------
// Declarations
export type Decl struct {
Node;
exported bool;
ident *Expr; // nil for ()-style declarations
typ *Type;
val *Expr;
// list of *Decl for ()-style declarations
// list of *Stat for func declarations (or nil for forward decl)
list *List;
}
export func NewDecl(pos, tok int, exported bool) *Decl {
d := new(Decl);
d.pos, d.tok, d.exported = pos, tok, exported;
return d;
}
export var BadDecl = NewDecl(0, Scanner.ILLEGAL, false);
// ----------------------------------------------------------------------------
// Program
export type Comment struct {
pos int;
text string;
}
export func NewComment(pos int, text string) *Comment {
c := new(Comment);
c.pos, c.text = pos, text;
return c;
}
export type Program struct {
pos int; // tok is Scanner.PACKAGE
ident *Expr;
decls *List;
comments *List;
}
export func NewProgram(pos int) *Program {
p := new(Program);
p.pos = pos;
return p;
}
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